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1.
Kiyoshi Satouchi Kaoru Hirano Masamitsu Sakaguchi Hisaaki Takehara Fumito Matsuura 《Lipids》1993,28(9):837-840
The phospholipid and the fatty chain compositions of diacyl, alkylacyl and alkenylacyl glycerophospholipids of the free-living
nematode,Caenorhabditis elegans, were investigated. The phospholipids were comprised of 54.5% ethanolamine glycerophospholipid (EGP), 32.3% choline glycerophospholipid
(CGP), 8.1% sphingomyelin and 5.1% others. The most abundant fatty acid in CGP was eicosapentaenoic acid (20∶5n−3). The fatty
acids in CGP were more unsaturated than those in EGP. Alkenylacyl and alkylacyl subclasses accounted for 1.0 and 2.6%, respectively,
of CGP and 14.0 and 19.6%, respectively, of EGP. At least 80% of the alkenyl and alkyl groups were 18∶0 chains and the remaining
were odd numbered chains. The potential presence of platelet-activating factor (PAF) was examined by bioassay, but PAF-like
activity was not detected in the extracts of this nematode. 相似文献
2.
The metabolism of various dietary sterols and the effects of an azasteroid on sitosterol metabolism in the free-living nematodeCaenorhabditis elegans was investigated. The major unesterified sterols ofC. elegans in media supplemented with sitosterol, cholesterol or desmosterol included 7-dehydrocholesterol (66.5%, 40.5%, 31.2%, respectively),
cholesterol (6.7%, 52.3%, 26.9%), lathosterol (4.4%, 3.6%, 1.7%) and 4α-methylcholest-8(14)-en-3β-ol (4.2%, 2.1%, 3.8%). Esterified
sterols, representing less than 20% of the total sterols, were somewhat similar except for a significantly higher relative
content of 4α-methylcholest-8(14)-en-3β-ol (23.3%, 23.4%, 10.6%). ThusC. elegans not only removes the substituent at C24 of dietary sitosterol but possesses the unusual ability to produce significant quantities
of 4α-methylsterols. WhenC. elegans was propagated in medium supplemented with sitosterol plus 5 μg/ml of 25-azacoprostane hydrochloride, the azasteroid strongly
interfered with reproduction and motility ofC. elegans and strongly inhibited the Δ24-sterol reductase enzyme system; excluding sitosterol, the major free sterols of azacoprostane-treatedC. elegans were cholesta-5, 7, 24-trien-3β-ol (47.9%), desmosterol (9.4%), fucosterol (2.1%) and cholesta-7,24-dien-3β-ol (2.0%). These
4 sterols are likely intermediates in the metabolism of sitosterol inC. elegans. 相似文献
3.
The behavioral responses by the nematodeCaenorhabditis elegans to 12 organic compounds was explored using tethered nematode and computer tracking methods. Results indicate that the nematode is attracted to acetone, diethyl ether, isoamyl acetate, isoamyl alcohol, 2,4-pentanedione, andn-propanol. No responses were detected to acetaldehyde, acetylcholine, ethanol, formaldehyde, i-propanol, and valerate. Isoamyl acetate and acetone were found to be the most potent attractants eliciting minimal responses at concentrations near 10?10 M. The geometry and charge distribution of a single hypothetical receptor that would interact with all the compounds that elicited a response and none of the compounds that failed to elicit a response is explored. 相似文献
4.
David B. Dunsenbery 《Journal of chemical ecology》1985,11(9):1239-1247
A new method is used to analyze responses to changes in the concentration of two chemical stimuli. Nematodes are allowed to move around on the surface of a thin layer of agar across which a stream of air blows to carry volatile stimuli. Darkfield illumination provides high-contrast images of the worms which are acquired by a video camera and fed to a microcomputer which is programed to simultaneously track and record the movements and changes in direction of as many as 25 animals. The results are reported in real time. The worms respond to an increase in CO2 concentration by decreasing the number moving and increasing the number of changes of direction. Both responses adapt to steady-state levels in about half a minute. This suggests that they respond by changing the probability of initiating a reversal bout. This observation adds a repellent to the class of stimuli thatC. elegans reponds to by klinokinesis. The resonses to changes in oxygen concentration are somewhat different. Movements and changes in direction both decrease when the oxygen concentration falls and increase when the concentration rises. No adaptation is seen within the one-minute time span observed. This observation provides further evidence that the response to oxygen differs from the response to other chemicals and may be sensed internally. These observations demonstrate that computer tracking is a sensitive method of analyzing animal behavior. It is further demonstrated that a significant response can be detected to a relatively weak stimulus in less than 5 min. 相似文献
5.
David J. Chitwood William R. Lusby Malcolm J. Thompson Jan P. Kochansky Oliver W. Howarth 《Lipids》1995,30(6):567-573
Caenorhabditis elegans was cultured in semi-defined medium containing yeast extract, soy peptone, glucose, hemoglobin, Tween 80, and sitosterol.
Monoglycosylceramides were chromatographically purified from nematode extracts. Their structures were elucidated with mass
spectrometry, nuclear magnetic resonance spectroscopy, and analysis of methanolysis products of the parent cerebrosides. The
glycosylceramides were unusual in that the only long-chain sphingoid base detected was aniso-branched compound with a C-4 double bond (i.e., 15-methyl-2-aminohexadec-4-en-1,3-diol). Glucose was the only sugar moiety
detected. The fatty acids consisted of a series of primarily straint-chain, saturated, 2-hydroxylated C20–C26 acids; someiso-branched analogs also occurred. The sphingomyelins ofC. elegans were also hydrolyzed, and the sameiso-branched C17 compound was the only sphingoid base detected. This is the first structural analysis of a nematode glycosphingolipid and
the first report of an organism in which the long-chain sphingoid bases are entirelyiso-branched.
Fatty acids are represented by a binumeric system in which the first number refers to the chain length, and the second number
refers to the number of double bonds. 相似文献
6.
Tamotsu Tanaka Kouji Ikita Tetsuji Ashida Yoshiaki Motoyama Yasunori Yamaguchi Kiyoshi Satouchi 《Lipids》1996,31(11):1173-1178
The effects of growth temperature on the fatty acid compositions of the phosphatidylcholine (PC), phosphatidylethanolamine
(PE), and total lipid (TL) fractions of the free-living nematodeCaenorhabditis elegans were investigated. A reduction in growth temperature from 25 to 15°C caused the proportions of eicosapentaenoic acid (20∶5n-3)
to increase from 23.6 to 32.5% in the PC, from 7.4 to 10.8% in the PE, and from 12.9 to 19.9% in the TL fractions. Conversely,
the levels of dihomo-γ-linolenic acid (20∶3n-6) and arachidonic acid (20∶4n-6) in these phospholipid fractions and the TL
fraction both decreased with decreasing growth temperature. Analysis of the positional distribution of fatty acids in the
PC fraction revealed that the change in the composition of C20 polyunsaturated fatty acid was obvious in positionsn-2. Lowering the growth temperature induced an increase in the level of the diacyl subclass of PE from 58% at 25°C to 71%
at 15°C, with a concomitant decrease in the levels of the alkylacyl and alkenylacyl subclass of PE ofC. elegans. These changes observed in the phospholipids ofC. elegans might be one mechanism for adaptation to low temperature. Lipids 31, 1173–1178 (1996). 相似文献
7.
Bowman O. Davis Jr. Marian Goode David B. Dusenbery 《Journal of chemical ecology》1986,12(6):1339-1347
Amphid sensilla, historically considered the primary chemosensory structures of nematodes, were found to be necessary for the detection of only one of the six chemical stimuli that were tested. Only the attraction to cAMP was eliminated by damaging the two lateral lips, which bear the amphid sensilla. The inner labial sensilla, one of which occurs on each of the six lips, are probably the primary receptor structures for the other chemical stimuli. Damaging all six lips, which should destroy all anterior chemosensory input, not only eliminted the attraction to sodium and chloride ions, but reversed the nematodes' response to them. Nematodes with all six lips destroyed showed reversal behavior when exposed to these attractants. Nematodes with damage to all six lips appeared to recover much of their normal chemosensory function within 24 hr after treatment. 相似文献
8.
《Fuel》1987,66(5):643-648
The possibility of dealkylation of ethylbenzene by the hydrogen generated in situ from methanol decomposition was investigated in a continuous reaction apparatus at temperatures of 650–950 °C, residence times of 6–33 s, sample flow rates of 0.4–0.9 g h−1 and ethylbenzene concentrations of 25–100 vol%. The main dealkylation products were benzene, toluene, styrene, methane and ethylene. Small amounts of condensation products were also identified by gas chromatography. The dealkylation of ethylbenzene was significantly promoted by the hydrogen generated from methanol, without any carbon or tar formation. Kinetic analysis was carried out, assuming first-order reaction. The activation energy of the total reaction was 209 kJ mol−1 and the frequency factor was 9.1 × 109s−1. 相似文献
9.
William R. Nes Antonio Alcaide Frank B. Mallory Josephine R. Landrey Robert L. Conner 《Lipids》1975,10(3):140-144
WhenTetrahymena pyriformis was incubated with sitosterol ([24R]-24-ethylcholest-5-en-3β-ol]) or itstrans-Δ22-derivative (stigmasterol), the C-24-dealkylated product, cholesta-5,7,trans-22-trien-3β-ol, was obtained in both cases. 24(S)-24-Ethylcholesta-5,7,trans-22-trien-3β-ol also was found to be a metabolite. When sitosterol was the substrate, 24(R)-24-ethylcholesta-5,7-dien-3β-ol was obtained as a third product. Identifications were made by mass spectroscopy, quantitative chromatography, labeling with14C, and by other means. The dealkylated product (cholestratrienol) represented 30% of the sterols isolable after incubation. The administration of sterols to this organism did not induce sterol biosynthesis, since 2-14C-mevalonate failed to yield radioactive sterol in the presence of added stigmasterol. 相似文献
10.
11.
此研究在长庆榆林气田根据膨胀制冷原理,结合其气田低温分离的特点,进行了天然气脱水脱烃的实验研究。长庆榆林气田目前多采用针阀节流的方式达到降压降温的目的,利用低温分离工艺进行天然气脱水、脱烃处理。对于井口压力低的井,采用针阀节流要达到低温分离目的所需的压降较大,达不到外输压力要求。在这种情况下,此研究使用膨胀制冷管开展实验研究,利用系统已有的背压条件取得相应的温度降,促进了气体中的游离水、重烃类的凝析。 相似文献
12.
Virgil I. Stenberg V.R. Srinivas Philip Sweeny R.J. Baltisberger N.F. Woolsey 《Fuel》1983,62(8):913-915
N,N-Dimethylaniline successively demethylates at 425 °C in the presence of hydrogen and hydrogen sulphide or sulphur to give successively N-methylaniline and aniline. For the dealkylation reaction, the rank order of promotors is S >SH2 >H2S >H2SH2 >H2. 相似文献
13.
F. H. Smith 《Journal of the American Oil Chemists' Society》1974,51(9):410-412
Details for the germination of cotton seedlings and their utilization for incorporating14C-labeled acetate into gossypol are presented. Methods for the isolation and purification of the biosynthesized gossypol are
given. The specific activity of the gossypol obtained from root tissue and cotyledons had mean values for 8 preparations of
428.6×103 and 6.3×103 dpm/mg, respectively. Corresponding incorporations were 5.42 and 0.32%.
Paper no. 4190, North Carolina State University Experiment Station, Raleigh, N.C. 相似文献
14.
Abstract The mechanism by which the phthalocyanine complex trisodium tetra-4-sulfonatophthalocyanineiron(JJJ) (Fe(TSPc)) promotes oxidation and dealkylation of non-phenolic benzyl alcohol units in lignin under alkaline conditions was investigated using simple lignin model compounds. The iron complex effectively oxidised benzylic hydroxyl groups in 2-hydroxyethyl apocynol (5), with the extent of oxidation increasing with the amount of Fe(TSPc) added. To a limited extent, Fe(TSPc) also catalysed the oxidation of 5 by small amounts of oxygen in the reaction mixture. However, the extent of oxidation did not increase on adding excess air or oxygen, as greater amounts of oxygen also increased complex degradation. Phenolic products were formed in these reactions in the presence of Fe(TSPc), but at a rate slower than that of the benzylic oxidation. Further experiments indicated that the phenolic products were formed by base-promoted loss of the ether group at C4 and that such dealkylation occurred more readily in oxidised products. 相似文献
15.
16.
Sheng H. Lin 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1993,58(2):159-163
Laboratory investigations of C.I. Disperse Red 60 adsorption on molecular sieves, activated alumina, granular activated carbon (GAC), diatomite and sawdust were conducted in this study. The effectiveness of those adsorbents for pollutant removal and color reduction of disperse dye was examined and compared with that of powdered activated carbon (PAC). It was found that the activated alumina has only 61% COD removal efficiency in comparison with that of PAC while those of molecular sieves, GAC and diatomite are much lower. In terms of color removal, activated alumina and molecular sieves are as effective as PAC while GAC, diatomite and sawdust are much less effective. The monolayer Langmuir isotherm was found to represent well the measured adsorption data and the constant parameters of the adsorption isotherm were determined for all adsorbents. The simplified mass transfer model proposed previously was also used for estimating the mass transfer coefficients using the initial adsorption data for several adsorbents. 相似文献
17.
Uptake of blood triglyceride by various tissues 总被引:3,自引:0,他引:3
Triglycerides are transported in the blood in chylomicrons and very low density lipoproteins. Electron microscopic studies
indicate that these particles, which range in diameter from 0.03–0.6 μ, cannot cross the capillary endothelium in most tissues.
There is now considerable evidence that the triglycerides are hydrolyzed to free fatty acids (FFA) during uptake and that
this process is catalyzed by lipoprotein lipase. The enzyme is found in nearly all tissues that utilize circulating triglyceride,
and the level of activity, in individual tissues, varies with nutritional and physiological states that affect triglyceride
uptake, such as fasting, diabetes and pregnancy. Studies in perfused adipose tissue with doubly labeled chylomicrons showed
that hydrolysis occurs outside of the blood stream. Two-thirds of the fatty acids are incorporated into tissue triglyceride
and the rest are release as FFA, with glycerol, to the blood. Infusion of heparin causes immediate release of lipoprotein
lipase activity to the blood and decreases the amount of chylomicron-triglyceride hydrolyzed by the tissue. Electron microscopic
cytochemical studies showed that hydrolysis of blood glycerides by lipoprotein lipase in adipose tissue occurs within the
capillary endothelial cells and in the subendothelial space near the pericytes, but not in the capillary lumen or near the
fat cells. The results indicate that the fatty acids of chylomicrons cross the capillary endothelium as glycerides and FFA,
within a membrane-bounded system, and cross the extravascular space to the fat cells as FFA.
Presented at the AOCS Meeting, Atlantic City, October 1971. 相似文献
18.
Radek Zaleski Wojciech Stefaniak Małgorzata Maciejewska Jacek Goworek 《Journal of Porous Materials》2009,16(6):691-698
The porosity of porous copolymer 1-vinyl-2-pyrrolidone-divinylbenzene has been studied by nitrogen adsorption, temperature
programmed desorption, and positronium annihilation lifetime spectroscopy. It was shown that the pore structure characteristics
depends on the swelling of the polymer material in various solvents. The structural features of polymeric materials restructured
under different conditions are described and the structural changes are discussed. The applicability of PALS technique in
structural investigations is presented. 相似文献
19.
A recent study on the metabolism of 1-14C-α-linolenic acid in the guinea pig revealed that the fur had the highest specific activity of all tissues examined, 48 h
after dosing. The present study investigated the pattern of tissue lipid labeling following an oral dose of 1-14C-linoleic acid after the animals had been dosed for the same time as above. Guinea pigs were fed one of two diets with a
constant linoleic acid content (18% total fatty acids) and a different content of α-linolenic acid (0.3 or 17.3%) from weaning
for 3 wk and 1-14C-linoleic acid was given orally to each animal for 48 h prior to sacrifice. The most highly labeled tissues (dpm/mg of linoleic
acid) were liver, followed by brain, lung and spleen, heart, kidney and adrenal and intestines, in both diet groups. The liver
had almost a three-fold higher specific activity than skin and fur which was more extensively labeled than the adipose and
carcass. Approximately two-thirds of the label in skin plus fur was found in the fur which, because of a low lipid mass, would
indicate that the fur was highly labeled. All tissues derived from animals on the diet with the low α-linolenic acid level
were significantly more labeled than the tissues from the animals on the high α-linolenic acid diet, by a factor of 1.5 to
3. The phospholipid fraction was the most highly labeled fraction in the liver, free fatty acids were the most labeled fraction
in skin & fur, while triacyglycerols were the most labeled in the carcass and adipose tissue. In these tissues, more than
90% of the radioactivity was found in fatty acids with 2-double bonds in the tissue lipids. These data indicate that the majority
of label found in guinea pig tissues 48 h after dosing was still associated with a fatty acid fraction with 2-double bonds,
which suggests there was little metabolism of linoleic acid to more highly unsaturated fatty acids in this time frame. In
this study, the labeling of guinea pig tissues with linoleic acid, 48 h after dosing, was quite different from the labeling
with α-linolenic acid reported previously. The retention of the administered radioactivity from 14C-linoleic acid in the whole body lipids was 1.6 times higher in the group fed the low α-linolenic acid diet (diet contained
a total of 1.8 g PUFA/100 g diet)compared with the group fed the high α-linolenic acid diet (diet contained 3.6 g PUFA/100
g diet). The lack of retention of 14C-labeled lipids in the whole body would be consistent with an increased rate of β-oxidation of the labeled fatty acid on
the diet rich in PUFA, a result supported by other studies using direct measurement of labeled carbon dioxide. 相似文献
20.
A study was made of the catalytic graphitization of carbons by 22 kinds of metals. Heat treatments were carried out at 2600°C for 1 hr and 3000°C for 10 min under argon atmosphere. In graphitizing 3,5-dimethylphenol-formaldehyde resin carbon powder with which 20w/o metal powder (Al, Cr, Mn, Fe, Co, Ni, Ca, Ti, V, Mo and W) was mixed, graphitic carbon was catalytically formed. The first six metals, which belong to the carbon dissolution-precipitation mechanism, gave large graphitic crystal flakes at an early stage of the reaction; the other metals resulted in fine crystals through the carbide formation-decomposition mechanism. For the non-graphitizing phenol formaldehyde resin carbon in which 10w/o metal powder was dispersed, Mg, Si, Ca, Cu and Ge catalyzed formation of only graphitic carbon; and Al, Ti, V, Cr, Mn, Fe, Co, Ni, Mo and W formed both graphitic and turbostratic carbons. Except for Al and Cu, the former effect was exerted by non-transition metals and the latter effect by transition metals. Boron alone markedly accelerated homogeneous graphitization of both kinds of carbon; and Zn, Sn, Sb, Pb and Bi had no catalytic effect. On the basis of these results, the relationships between some properties of the metals, their catalytic abilities and the kind of catalytic effects are discussed. 相似文献